A survey by an anti-bullying charity has discovered that one in three youngsters could have been the victim of cyberbullying.
A poll of 2,000 11 to 18-year-olds by BeatBullying discovered an alarming growth in the use of technology like social networking sites and SMS messaging.
Girls are four times more likely to be on the receiving end of cyberbullying than boys.
The research was released to boost the profile of BeatBullying's CyberMentors campaign, which has been backed by Prime Minister Gordon Brown.
"CyberMentors is an exciting new initiative to help keep Britain's children and young people safe online," said the PM.
"The internet provides children and young people with a world of entertainment, opportunity and knowledge, a world that is quite literally at their fingertips, just the click of a mouse away.
"Just as we wouldn't let them go unsupervised in playgrounds or in youth clubs, so we must put in place the measures that we need to keep our children and young people safe online.
"Cyberbullying is the most common problem experienced by young people on the internet, so I am delighted that BeatBullying is taking a lead in training more than 3,000 CyberMentors to take its successful peer mentoring programme into schools and to establish it online."